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Resistance based process control device diagnostics

  • US 6,434,504 B1
  • Filed: 08/06/1999
  • Issued: 08/13/2002
  • Est. Priority Date: 11/07/1996
  • Status: Expired due to Term
First Claim
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1. A process control device in a process control system, comprising:

  • an electrical element having an electrical resistance;

    a device output adapted to couple the device to a process control loop;

    an ambient temperature sensor configured to sense an ambient temperature which affects the electrical resistance of the electrical element;

    an electrical element self-heater coupled to the electrical element configured to provide a self-heating signal related to a self-heating index of the electrical element due to the electrical resistance and as a function of the sensed ambient temperature, the sensed ambient temperature correcting for errors in the measurement of the self-heating index;

    element diagnostics coupled to the self-heater responsively providing a diagnostic output related to health of the electrical element as a function of the self-heating signal.

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